Free-tripping overload switch



June l2, 1951 A, w, KR|EGER 2,556,197

FREE-TRIPPING ovERLoA'D swITcH Pilduune 27, 1949 2 sheets-sheet 1 June 12, 1951 A. w. KRIEGER FREE-TRIPPING OVERLOAD SWITCH 2 Sheets-Sheet 2 Filed June 27, 1949 Patented June 12, 1951 FREE-TRIPPING OVERLOAD SWITCH Alvin W. Krieger, Milwaukee, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application June 27, 1949, Serial No. 101,601

This invention relates to free-tripping overload switches, and while not limited thereto, particularly to switches of the character described adapted for use in aircraft of the like wherein a high degree of reliability and high electrical capacity in small sizes are paramount. A primary object of the invention is to provide a snap acting switch with means for automatically tripping the switch on the occurrence of predetermined overload of high reliability and more particularly to render such automatic tripping free from interference by the normal switch actuating means and without dependence upon any part thereof. i

Another object is to provide a switch of the character described which has a high capacity for its size.

Another object is to provide a switch of the character described having adequately powerful tripping means in the event its contacts become welded.

Another object is to provide a switch of the character described wherein the contact opening forces on overload tripping may be varied without interference with the normal operating means provided.

Another object is to provide a switch of the .character described which will have a relatively low cost and be easy to assemble and more particularly to provide a switch mechanism affording the desired functions which may be easily and inexpensively assembled into a unitary molded insulating base adapted for simple and expeditious mounting to suitable supporting structure.

Another object is to provide in a switch of the character described, means for indicating a tripped condition of the switch and more particularly to indicate such condition by positive movement and retention of the normal operating means to a predetermined position without dependence upon the normal switch actuating means.

Another object is to provide in a switch of the character described for positive resetting of the tripping mechanism by movement of the normal operating means and more particularly to attain such resetting 'without dependence upon the snap acting mechanism and while maintaining the switch in open circuit condition.

Another object is to improve the details of construction and the operation of switches of the aforementioned character. l

Other objects and advantages of the invention will hereinafter appear.

9 Claims. (Cl. 200-116) The accompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification within the scope of the appended claims.

In the drawings:

Figure 1 is an enlarged top plan View of a switch constructed in accordance with the invention.

Fig. 2 is a vertical sectional view, on the line 2-2 of Fig. 1; the full line representation of the switch parts illustrating the open circuit position thereof while the dotted line representation illustrates the position of certain parts in the closed or on position of the switch.

Fig. 3 is a side elevational view of the switch, the insulating enclosure being sectioned to expose the switch parts, which are shown in the tripped position. l f' Fig. 4 is a top plan view of the switch with the cover plate and associated operating lever removed to expose the remainder of the switch parts. f

Fig. 5 is a fragmentary sectional view of 'a portion of the operating lever; I r

Referring to the drawings, the reference numeral I0 designates a one-piece molded insulating base having a recess I0*i opening to the upper surface thereof for enclosing and supporting the switch mechanism. A stationary contact II of slightly resilient electrically conductive metal is mounted on thebottom wall of said recess I Ila and rigidly and permanently attached to base I0 and a terminal lug I2 of well known form as by rivets I3, which provide electrical conductivity between said stationary contact II andk lsaid terminal lug I2. A U-shaped contactor I4 best shown in Fig. 3 is provided'to cooperate with said stationary contact II, said contactor I4 being pivotally attached to a rectilinearly movable'element I5 as at I 4.

Element I5 is of an inverted U-shape vand is movable rectilinearly within vertical grooves IIIb provided on the inner side walls of base Ill, said element I5, as best shown in Fig. 4, being provided with pairs of outwardly extending portions |58, one at each corner thereof; for guidance within said grooves IIIb. Element I5 is normally'biased downwardly by a relatively heavy helical spring I6, the lower end of whichencircles a pin I5b rigidly attached to and supported by a' laterally extending ear I5c of element I5. The upper end of spring I6 abuts a mounting plate I1 provided to cover the open end of base III and preferably rigidly attached thereto as by rivetsll.V

engagement of contactor I4 with stationary contact II, while counter-clockwise movement of toggle member 23 from the dotted line representation of Fig. 2 will similarly result in disengagement of the contacts with a snap action while the switch mechanism is latched as previously described.

In the event that the switch is tripped by an overload and the circuit opened as hereinbefore described, the switch parts will take the positions shown in Fig. 3. It will be :apparent that in this position clockwise movement of toggle member 23 about its pivot at 26a by movement of operating lever 24 to the left or on position, cannot result in closing of the switch contacts since in the tripped condition downward movement of rectilinearly movable element I5 has carried the pivoted end of contactor I4 downwardly a corresponding distance and projections I I)c of base I 0 block movement of contactor I4 to the closed circuit position, thus rendering the switch mechanism trip-free.V Should it be attemped to reset the tripping mechanism and to close the switch contacts while the overload persists, latching means I8 would again allow the switch to trip open regardless of whether or not operating lever 24 were held in the on position.

It will be further noted that upon tripping of thev switch by downward movement of element I5, the tension of over-center spring 25 is lessened suiciently to permit a relatively light helical spring 29 connected between pin 28 on toggle member 23 and a lug 2I5d provided therefore on one of the horizontally extending arm 26c of member' 26 to carry toggle member 23 in a lcounter-clockwise direction, which movement, however, is limited by a stop afforded by engagement of an extension 23d on one end of said member 23 with element I5 now in its downwardly biased position. The parts are so proportioned as to limit the aforementioned movement of toggle member 23 to carry operating lever 24 to a position intermediate its extreme operating positions and for retention there to indicate the tripped condition of the switch. Thus it will be apparent that provision is made for positive indication of such tripped condition of the switch without dependence upon the u operation of over-center spring 25, thereby insuring reliable indication of the condition of the switch.

The aforementioned engagement of portion 23d of toggle member 23 with element I5 in its downwardly biased position, additionally conv stitutes ameans for relatching of the latching means I8 inasmuch as movement of lever 24 to the off position results in counter-clockwise movement of toggle member 23 against element l5 and its biasing spring IIS, thus tending to raise element I5 to a point where bimetallic element I8a may again engage the underside of lug I5d of element I 5. As will be apparent, the aforedescribed resetting is accomplished without dependence on over-center spring 25 and since resetting is afforded by movement of operating lever 24 to the off position, such resetting is accomplished while the switch contacts are maintained open. The circuit may then be closed by movement of operating lever 24 to the closed or on position through the normal snap acting means hereinbefore described.

'Ihe switches illustrated in the drawings, additionally show a dust boot assembly of the type disclosed in my copending application, Ser. No.

6. 64,077, comprising a dust boot 30 and a member 3l for clamping the boot 3B to base I0 to overlie mounting plate I'I, the latter also having a pair of self-locking nuts 32 (Fig. 2) of well known type for mounting of the switch to suitable supporting structure.

I claim:

1. A free-tripping overload vswitch comprising, in combination, a rectilinearly movable element biased in one direction, cooperating contacts including a contactor pivotally supported on said element, thermally responsive latching means restraining said element against its bias, to release said element upon the occurrence of an overload, operating means for said contactor to engage and disengage said contacts at will while said element is latched and to relatch said element while maintaining said contacts disengaged, and a iixed part against which said element when released, drives said contactor for pivotal movement of the latter for disengagement of said contacts free from interference by said operating means.

2. A free-tripping overload switch comprising, in combination, a rectilinearly movable element biased in one direction, cooperating contacts including a contactor pivotally supported on said element, thermally responsive latching means restraining said element against its bias, to release said element upon the occurrence of an overload, snap action operating means for said contactor to engage and disengage said contacts at will while said element is latched and to relatch said element while maintaining said contacts disengaged, and a xed part against which said element when released/drives said contactor for pivotal movement of the latter for disengagement of said contacts free from interference by said operating means.

3. A free-tripping overload switch comprising, in combination, a rectilinearly movable element biased in one direction, cooperating contacts including a contactor pivotally supported on said element, thermally responsive latching means restraining said element against its bias, to release said element upon occurrence of an overload, operating means for said contactor to engage and disengage said contacts at will while said element is latched and to relatch said element when released, said operating means comprising a member movable to one position for engagement of said contacts and to another position for disengagement of said contacts and relatching said element, a xed part against which said element when released drives said contactor for pivotal movement of the latter for disengagement of said contacts, said operating means being non-interfering with contact disengagement by the last mentioned movement of said contactor but being responsive thereto for movement of said member to an intermediate position.

4. A free-tripping overload switch comprising, in combination, a rectilinearly movable element biased in one direction, cooperating contacts including a contactor pivotally supported on said element and a resiliently mounted stationary contact, thermally responsive bimetal latching means restraining said element against its bias, to release said element upon the occurrence of an overload, snap action operating means for said contactor to engage and disengage said contacts at will while said element is latched and to relatch said element while maintaining said contacts disengaged, and a fixed part against which agarre;

said elementf when. released drivesxsaidzcontactor for pivotal movementI of", the .latter viforylpositive disengagement of fsaid contacts :Without dependence on. said operatingmeans.

'5. A free-:trippingoverload switch comprising, in combination, a rectilinearly-amovab1e element having a normal fixed position, cooperatingrcontactsA -including a contactor {pivotallyl supported by said element, operatingmeans'forgsaidfcontactor .to engage and disengagefsaid contactor; at

.will while saidelement occupies said normalposition, an overload responsive thermal latch restraining said element in said 4normal position, -means --to effect Vindependently. ofsaid operating means Vand free '-from interference therefrom movementof said element-and Vresultingfdisengagement of said contacts when said latch trees said element, and interconnections between the rst mentioned means and said element vproviding for resetting'of the latter by 'movement of Ya part of the'former to contact disengagingpo'sition and for ldefining an indicating posi-tionfo'f such part upon disengagement 01 said contacts as the result of movement of saidrectilinearly movable element upon overload.

6. A free-tripping over/load switch comprising, in combination,4 a rectilinearly movable element biased in one direction, cooperating contacts including a contacter pivotally supported on said element, an enclosure for said switch guiding sa-id rectilinearly movable element, thermally -responsive latching meansrestraining said element against its bias, to, release saidelement Yupon the occurrence of an overload,A operating means for said contacter to engage and disengage said conl tacts at will Whilefsaid element is latche'd and'to relatch said element when released,-said enclosure having a Xed part against which said element when released drivessaid contactor for pivotal movement of the latter Vfor v disengagement of said contacts independently-of said operating means, the latter .being responsiveto said last mentioned movementof'saidcontactor 'for movementgto an int'ermediatepositionindicating a tripped condition ofthe switch.

7. A free-tripping'overload switch-comprising,

in combination a reciprocableelementbiased'in Vfor pivotal movement of ,the latter .for positive disengagement of said contacts independentlyof said operating means, the latterbeing responsive to said movement of said contactor for movement of said operating means to aninterme'diate X97 s position :and: into :engagementiwith xsaidelement, which .saiords a stop:for-said ;operating lmeansfor indicating-1 a tripped condition. of ttheL-Switchrand for relatching of, saidrelement.

18. A free--tripp'ingoverload:switchy comprising, in combination, a rectilinearly movable element, means biasing said element inoneidirectiongcooperatingHcontactsincluding a `contactar :pivotally supported yon said element, thermallyv rresponsive. latching means restraining said element against Vitsbiasto release said element uponioccurrence of .an overload, operating meansforzsaid contacter including aniover-centerspring to" engage and `disengage said vcontacts at Vwill f1 withY a snap action while: saidaelement isrlatchedV and-to relatch said elementwhen releasedrandsalifxed `part against which. said .element when released drives said contactor' for'pivotal movement ofthe latter for disengagement Lof saidcontactsfsaid operating means being non-interferingwitlrconvtact disengagement :by the ylast lmentioned movement and said,disengagement'being effected by response of said element Ato its said lbiasing means and without idependence on said overcenter spring.

9. A free-tripping overload switch'comprising, in combination,v a rectilinearly movable'element biased in one direction, cooperating conta'ctsincluding a contactor pivota1ly=fsupported onsaid element, a one-piece insulating-'enclosure for said switch having grooves `to guide said movable `element, thermally vresponsive latching means restraining said' element against its' bias to release said element upon the occurrence vof an overload, andsnap :acting operating means forsaid contactor including an over-center spring and a member movable to. onefpositionfor engagement of Asaid contacts and'to another positionfor 'disengagement of said contacts-andrelatching of said element without dependence on said overcenter spring,-said insulating enclosure having an integrally forme'd'xed'part against which said element whenl released drives saidfcontactor v'for pivotal movement of the latter for positive disengagement of. sai'dcontacts Without dependence on said over-'center spring,.and ysaid operating means being non-interfering withV contact disengagement by rthe'last mentioned movement of 'saidcontactor'butbeing responsive thereto for movement of itsisai'd memberto an intermediate position and'into engagement-with said element.

ALVIN'W. KRIEGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES @PATENTS Number Name Date v1,726,233 KrantzV Aug. 27,'1929 2,222,209 Werner INov. 191940 

